1. Field of the Invention
The present invention relates to alleviation of motor control problems. More particularly, the present invention relates to a computerized method of improving motor control in an individual via somatosensory, proprioceptive and/or kinesthetic sensory training.
2. Description of the Related Art
Motor control problems in individuals are rooted in a variety of different causes, including traumatic injury, disease, aging and gradual xe2x80x9coccupationalxe2x80x9d type injury. If the affected individual is motivated enough to participate in a rehabilitative training program, recovery is possible and is highly dependent on the quantity and quality of the training program.
In cases where motor control problems in individuals are caused by traumatic injury to or disease of the muscle(s) and/or related nerve(s), depending on the extent of injury to the nerve(s), such individuals may or may not experience a corresponding loss of sensory ability. Typical causes of injuries include trauma, stroke, aneurysm, and invasive surgery. Examples of diseases include meningitis and cancer. Historically, regardless of whether the motor control problem is accompanied by a loss of sensory ability, these individuals have been treated with strengthening, flexibility, conditioning and motor retraining techniques, with limited success.
Often, motor control problems are not caused by injury or disease, but are associated with a gradual degradation of motor control over time. Examples include work-induced focal dystonia, Alzheimer, torticollis, cerebral palsy, multiple sclerosis and movement disorders in Parkinson""s Disease, Huntington""s Chorea, and in other progressive neurological illnesses.
A common origin of focal dystonia is as a component of a repetitive strain injury (RSI) which appears to be the result of attended rapid movements repeated over a relatively long period of time. Generally, these potentially harmful rapid movements occur at a frequency at or below about 100 milliseconds. Typical symptoms of RSI include loss of motor control and involuntary movements of the affected hand, foot, limb or neck of the affected individual.
One example of rapid movements involves musicians and typists, or other skilled manual workers who are required to repeatedly execute rapid alternating movements, e.g., to produce trills and keyboard strokes, to perform a particular assembly line task, etc. When executed repeatedly over a period of time, these rapidly alternating movements put one at risk for RSI.
In a study involving musicians with focal hand dystonia, subjects shared common histories of increased practice and of extended, demanding performances under stressful conditions prior to the onset of the disabling symptoms. While most of their biomechanical tests were normal, there was a clear asymmetry in passive finger spread in the central digits, forearm and shoulder rotation. These motor control limitations forced some of the musicians to adopt compensatory awkward end range postures which in some cases caused inflammatory problems of the capsule, ligaments, tendons and fascia, i.e., typical RSI symptoms.
Potentially harmful rapid movements also include rapid simultaneous movement of adjacent portions of a limb which can otherwise be controlled independently, e.g., when multiple digits of one hand, are opened and closed rapidly. In one study involving primates, attended repetitive activities, under the conditions of high cognitive drive were conducted over a three month period.
In one experiment, the monkeys placed a hand on two bars that passively spread apart within 20 milliseconds. The monkeys were required to squeeze the palm and the digits against a hand piece while maintaining close contact with the hand piece during the entire movement trial. The hand piece opened between one and seven times per trial for a total of 1300 repetitions in a training session. In a second experiment, the monkeys were required to repetitively squeeze the hand piece. A successful trial required full hand contact, 80 grams of force, squeezed for 500-1000 milliseconds. Each successful trial was rewarded, with approximately 400 trials completed per training session.
Following about eight weeks of training, despite continued rewards, these monkeys began to avoid training. For example, they began to decrease the time and repetitions of the sessions and would lick their thumbs or hand as if it was painful. They also developed some compensatory strategies such as reducing the intensity of the grasp on the hand piece and/or using an arm pulling instead of the required hand squeezing strategy. When training was continued, symptoms of an occupationally induced RSI emerged in all five subject monkeys after approximately five weeks. Four of the five monkeys showed signs of inefficient motor control of the required tasks as well as in other non-trial movements such as retrieving food. The fifth monkey developed the most serious dystonic movements in the fourth digit of the trained hand.
Hence, it appears that subjects who suffer from RSI can develop a form of focal dystonia, a disorder of motor control manifested in a specific context during rapid skilled, attended movements. Unlike traumatic injury patients, most RSI subjects experience a slow onset of symptoms, often beginning as a feeling of awkwardness, fatigue, or impaired timing or force. Eventually, if the potentially harmful repetitive movements are continued, the degradation of motor control is often preceded, paralleled or followed by painful inflammatory problems of the capsule, ligaments, tendons and fascia.
Conventional RSI treatment such as strengthening, flexibility, conditioning and motor retraining exercises appear to offer only temporary relief. This is because the conventional treatments are directed at the symptoms and but do not attempt to identify nor address the source of the problem. As a result, despite rest and conventional treatment, the motor control problems and any accompanying inflammation often return as soon as the subjects attempt to resume the repetitive movements.
In view of the foregoing, there are desired improved techniques for addressing motor control problems accompanied by sensory degradation using a training regimen that addresses the root of the motor control problem and not just the symptoms of motor control. Such a regimen should offer a comprehensive solution thereby enabling the affected individuals to substantially regain normal motor control over the longer term.
The present invention provides a method and apparatus for implementing a training regimen that addresses motor control problems accompanied by sensory degradation. Accordingly, the training regimen is applicable to motor control disorders associated with a variety of different causes, including traumatic injury, disease, aging and gradual xe2x80x9coccupationalxe2x80x9d type injury.
For example, in an individual suffering from repetitive strain injury (RSI), the disabling motor control problems are often accompanied by sensory problems. These sensory problems do not appear to result from a peripheral nerve injury or disease. Instead, it appears that over time harmful attended rapid repetitive movements cause undesirable changes in the somatosensory, proprioceptive and/or kinesthetic ability of the affected regions of the individual. Briefly, somatosensory inputs include the light and deep tactile inputs, stretch, slow and rapidly adaptive tactile and vibratory tactile inputs. Proprioception and kinesthesia involve inputs from muscles, joints and skin contributing to movement control and locational sense control, respectively.
These sensory problems manifest themselves in a variety of symptoms. While some individuals with hand dystonias are able to differentiate light touch from deep touch, or sharp from dull pressure, they are unable to accurately interpret tactile cues through the skin, muscle afferents or tendons relative to location. In other words, these individuals appear to retain the ability to sense gross inputs but are unable to differentiate between the afflicted regions, i.e., there is a loss in sensory differentiation of the afflicted regions. For example, some individuals have difficulty determining which finger was stimulated, or whether one or more fingers were receiving the stimulus.
In some individuals, the motor control disorder includes involuntary motor control: co-contraction of flexors and extensors, inaccuracy, weakness, fatigue, loss of coordination and involuntary dystonic movements, e.g., when a hand touches a specific target interface. As a result, the individual can no longer perform tasks that require fine motor coordination of the affected portions.
The present invention hypothesizes that repetitive delivery of simultaneous or nearly simultaneous afferent sensory inputs, under attended conditions of high cognitive drive, results in a learning-induced integration of the representation of the individuality of otherwise differentiable parts of the subjects thereby degrading the sensory feedback loop necessary for normal motor control. Hence, the learning-induced progressive destruction of the otherwise highly differentiable representations of digit skin and of muscle afferent inputs involved with the muscles controlling the fingers is the root cause of the degradation of hand movement control. In other words, what started out as a degradation of the sensory feedback capability, essential for proper motor control, eventually manifests over time as a motor control problem.
As discussed above, motor control problems can also be the result of nerve injury or disease. In such cases, where nervous regeneration is possible, recovery can be enhanced by addressing the sensory degradation problem.
Thus, motor control problems accompanied by sensory degradation due to input integration or nerve damage/disease, can be alleviated by a regimen of remedial re-differentiating sensory training of the affected regions of the individual. Accordingly, the training regimen of the present invention differentially stimulates two locations within the afflicted portion of the individual. Feedback from the individual indicates the degree of difficulty the individual has in sensing differentially between the two locations. The stimulation is then adapted to the individual based on the feedback. Adaptation includes increasing the distance between the two locations and /or changing the spectral or temporal characteristics of the stimulation.
The present invention is effective and long lasting because the training regimen addresses a root cause of the motor control problem and not just the symptoms. These and other advantages of the present invention will be apparent upon reading the following detailed descriptions and studying the various figures of the drawings.